Apparatus for recovering acid and heat units thereof from digesters and for preparing digester liquor



June 7, 1932. J. STRINDLUND 1,362,243

APPARATUS FOR RECOVERING ACID AND HEAT UNITS THEREF FROM DIGESTERS AND FOR PREPARING DIGESTER 'LIQUR Original Filed March 28. 1927 Job/2 67117107000 H/lorney.

Patented June 7, 1932 UNITE STATES PATENTA- 0F l E.v

JOHN STRINDLUND, or mourn I HURUMLNORWAY, ASSIGNOR fro OHEMIJE'ULP rRooEss,

me, A CORPORATION on NEW YOR ArrARATUsroR nncovnnme ACID AND HEAT" onus THEREOF FROM. DIGESTERS Ann FOR PREPARING DIGESTER LIQUOR An apparatus for recovering acid and the heat units thereof from digesters and preparing and storing strong and hot boiling acid or digester liquor in the sulphite cellulose manufacture is previously known in the art, such apparatus comprising a receptacle containing acid into which gas and liquor from the digester when blown off are conducted directly and without being cooled, for the purpose of concentrating v the acid. Said prior apparatus is principally characterized in thatthe said receptacle is not closed, but isin open communication with one or more other, higher located receptacles in such manner that when drawing ofi' concentrated liquor from the lower receptacle, this lower receptacle is again automatically filled with acid from the higher located receptacle, which latter is in open communication with the atmosphere and is provided with an overflow drain so that the acid insaid latter receptacle is always maintained at a constant level, and a practically constant excess pressure corresponding to the difference in height between the receptacles is maintained in the lower receptacle. In the apparatus above referred to, two separate receptacles are used one of which is located at a certain height above the other, and which receptacles are connected with each other by means of two separate pipes. a Now, my present invention relates to'a simplification of the apparatus above referred to, and has for its purpose to make the ap- 'paratus cheaper to construct, and part cularly to simplify the alteration of such old installations for the purpose; in question,

which are provided with. a single receptacle, into the present apparatus for preparing digester liquor. For this purpose my present invention consists principally in that the two receptacles, or all receptacles, above referred to, consist of two or more compartments of a single receptacle which is vdivided by means of one or more partitions into two or more compartments located one above the other, and which are in open communication with one anotherthrough suitable openings in the partition or partitions in the same way as that above described in respectot the earlier apparatus. For the purposevof altering an old installation having a single receptacle 1nto my present improved apparatus is: thus only required to insert in such receptacle a partition having suitable openings. The cost of such change will therefore be very inconsiderable. r V v 1 In the accompanying drawing an apparatus according to my present invention'for' concentrating the raw digester liquor is illustrated in vertical section. r

In the construction illustrated in the draw ing a single receptacle 14 is used, which is divided by means of a partition 15 inserted therein into two compartments, namely an cal or in other manner slightly convex shape Application filed March 28, 1927, Serial No. 178,969, and in Sweden March 31, 1926; Renewed. J'iine 15,1931.

so that its middle portion is located somewhat higher than its. outer portions at the walls of the receptacle 14. In the middle and higher portion of the partition an opening is provided in which a short tube 4 is inserted which serves to conduct gas from the lower compartment to the upper compartment, and which for this purpose is in communication with a gas distributing tube 16 having fine orifices provided in the last mentioned compartment. In the outer and lower portions ofthe partition two openings areprovided in which short tubes 3 are inserted which are bent at an angle in the instance illustrated, and which serve to conduct liquor from one compartment to the other. A pipe 5 opens into the upper compartment 1, which pipe serves to admit the raw acid or liquor into said compartment. Said compartment 1 is also providedwith an overflow drain pipe 6 through which a possible excess of acid lead gas and liquor from the digester, which is not illustrated in the drawing, into said compartment, and is for this-purpose provided with a control valve 9. The lower compartment 2 is also provided with a. drain pipe 11 which serves to conduct the concentrated digester liquor to the digester. I

-Th e apparatus-described operates, in the followingmanner: The'coldraw acid from the acid preparation plant is admitted through the: pipe 5= into the upper compart- 'ment 1 and flows from said compartment through the tubes '3 into the lower compartmen-t Q- Which will thus be entirely filled with raw acid, while the upper compartment 1 will only be partly: filled', namely up to the overflow drain pipe 6. The liquid in the low-' er compartment 2 will thus be under a certain. pressure which is dependent upon the level of the liquid in the upper compartment 1'. When the' digester is blown otl the hot gas and liquorfrom the digester are led directly and without being cooled through the pi pe'8 into. the lower compartment 2. The

sulphurous acid introduced in. this manner into the said compartment-is absorbed-by the raw acid which is thereby heated. If more sulphurous acid is introduced into the compartment Q'than the acid in said compartment can absorb at the prevailing pressure and temperature, the excess gas passes through the tubes 4' and 1i6.tothe uppercoinpartment 1 and absorbed by thecooler' acid in said compartment. Owing to the volume increasi' ng when the gas andfliquor are admitted into the lower compartment 2 and heat the I acid in the same, a quantity of thezacid or liquor in the compartment 2 flows back to.v

the upper compartment '1 through the tubes The'excess of acid in the compartment 1' possibly caused hereby'fl'ows: off through the pipe 6', so that thelevel in the compartment 1 is still maintained constant. In this manner hot and strong digester-,liquor,-that is to say, liquor concentrated as much as possibl'e," is thus obtained in the lower compartment 2, while the compartmentl contains cooler acid which is only enrichedwith sulphu rous acid to a less extent. When the digester is tofbe charged for a new operation, hot concentrated. digester liquor is drawn from the lower compartment 2 through the pipe .11 and is introduced into the digester in the ordinary manner. According as digester liquoriis drawn in this man ner from the compartment 2, fresh and cold er acid flows from the upper compartment 1 through the tubes 3 so that the compartment 2' is always n'aintained filled. With the apparatus describeda digester liquor can thus be obtained which has the hi gh'est'and most uniform concentration possible.

In certain cases it maybe suitable to divide the receptacle 14. by means of several partitions 15 into more than two compartments which are placed in open communication with one another through suitable openings.

I claim:

1. Apparatus for recovering acid and the heat units thereof from digesters and for preparing digester liquor, comprisinga receptacle divided by partition means into superposed compartments, means for admitting c'oldi'aci'd liquorinto the uppermost compart ment, means for maintaininga constant level of acid l quor in said compartment, means foradmitting hot acid gas and liquid into the lowermost compartment, means for drawing ofi'f hot acid: liquor to be fedjto. a digester from said last mentioned compartment, the partition means having asubstantially convexshape, with its 'middleportion located higher than its outer portions and-beingpro.-. vided with an opening in its middle portion and with at least one opening in itsiouter portion, and a gasdistributing tube located partment, a pipe connected to the lower 1101?:

tion'of the receptacleforpassingfluid into,

the lowermost compartment of the receptacle,

an outlet pipe connected tow the lowermost compartment of the receptacle, afirst. passageway in the partition for leading'gas tromthe upper portion of the lowermost compartment into the lower portion of the'uppermost compartment, and a second passageway in the partition for leading liquor from; the lower portion of the uppermost compartment into the: upper portion ofthe lowermostcompartment, said passageways being so ar-f no ranged that acid liquorintroduced; into the uppermost compartment can completely thelowermos t compartment and: at least partially fi'll the uppermost compartmenuwherea 'bydarelatively tallcolumn of liquor ispro.- vi ed.

3. Apparatus for recovering acid andthe heat units thereof and for preparing cook ng liquor, comprising a single-closed receptacle, a partition inthereceptacledividing-the same into superposed compartments, apipe lead,-

ing intothe uppermost compartment fordischarging fresh cold acid liquor'into. that compartment, a pipe connected to. the lower portion. of the receptacle for passing fluid into the lowermost compartment of: the re-I ceptacle, anoutlet 1 pipe connected to the lower portion of the receptacle for passing liquor from the lowermost compartment of therecepta'cle-, 'a first passageway in the partition for leading gas'fromthe: upper portion of the lowermost compartment into the lower portion of the uppermost compartment, a second passageway in the partition for leading liquor from the lower portion of the uppermost compartment into the upper portion of the lowermost compartment, said passageways being so arranged that acid liquor introduced into the uppermost compartment can-completely fill the lowermost compartment and at least partially fill the uppermost compartment, whereby a relatively tall column of liquor is provided, and a pipe arranged at the upper portion of the uppermost compartment for maintaining aconstant level of liquor in the uppermost compartment.

4. Apparatus for recovering acid and the heat units thereof and for preparing cooking liquor, comprising a single closed receptacle, a partition in the receptacle dividing the same into superposed compartments, a pipe leading into the uppermost compartment for discharging fresh cold acid liquor into that compartment, a pipe connected to the lower portion of the receptacle for passing fluid into the lowermost compartment of the receptacle, an outlet pipe connected to the lower portion of the receptacle for passing liquor from the lowermost compartment of the receptacle, a first passageway in the partition for leading gas from the upper portion of the lowermost compartment into the lower portion of the uppermost compartment, a second passageway in the partition for leading liquor from the lower portion of the uppermost compartment into the upper portion of the lowermost compartment, said passageways being so arranged that acid liquor introduced into the uppermost compartment can completely fill the lowermost compartment and at least partially fill the uppermost compartment, whereby a relatively tall coumn of liquor is provided, and a pipe connected to the top of the receptacle for discharging gas from the upper portion of the uppermost compartment.

5. Apparatus for recovering acid and the heat units thereof and for preparing cooking liquor, comprising a single closed receptacle,

a partition in the receptacle dividing thesame into superposed compartments, a pipe leading into the uppermost compartment for discharging fresh cold acid liquor into that compartment, a pipe connected to the lower portion of the receptacle for passing fluid into the lowermost compartment of the receptacle, an outlet pipe connected to the lower portion of the receptacle for passing liquor from the lowermost compartment of the receptacle, a first passageway in the partition for leading gas from the upper portion of the lowermost compartment into the lower portion of the uppermost compartment, a second passageway in the partition for leading liquor from the lower portion of the uppermost compartment into the upper portion of the lowermost compartment, sald passageways being so arranged that acid liquor introduced into the uppermost compartment can completely fill the lowermost compartment and at least partially fill the uppermost v j compartment, whereby a relatively tall columnv of liquor is provided, and a perforated gas distributing tube connected to the partition and communicating with the first pasv sageway for distributing gas rising from the lowermost compartment into the acid liquor contained in the uppermost compartment.

. 6. Apparatus for recovering acid and the heat units thereof and for preparing'cooking liquor, comprising a single closed receptacle, a partition in the receptacle dividing the same into superposed compartments, a pipe leading into the-uppermost compartment for discharging fresh cold acid liquor into that compartment,a pipe connected to the lower portion of the receptacle for passing fluid into the lower most compartment of the receptacle, a pipe connected to the lower portion of the receptacle for passing liquor from the lowermost compartment of the receptacle, a first passageway in the partition for leading gas from the upper portion of the lowermost compartment into the lower portion of the uppermost compartment, and a second passageway in the partition for leading liquor from the lower portion of the uppermost 

